1. Field of the Invention
The present invention relates to a card connector mounted on electronic devices, such as cellular phones, telephones, PDAs (personal digital assistants), portable audio devices and cameras, and more particularly to a structure of a compact mechanism for reliably locking an IC card in the card connector.
2. Description of the Related Art
In electronic devices such as cellular phones, telephones, PDAs and cameras, a variety of functions are added by inserting an IC card with a built-in CPU or IC memory, such as a SIM (subscriber identity module) card, an MMC (multimedia card), an SD (secure digital) card, a Memory Stick (tradename) and a Smart Media (tradename).
A card connector structure for removably accommodating such an IC card has a plurality of contact terminals formed from metal leaf springs in a connector housing which are brought into contact with a plurality of contact pads formed on a front or back surface of the inserted IC card to electrically connect the IC card to the electronic device on which the connector is mounted. The contact pads of the IC card include a power supply pad connected to a power supply line and a plurality of signal pads for transferring a variety of signals. These pads are connected through the contact terminals of the card connector to the associated power supply circuit and a variety of signal processing circuits of the electronic device.
Many of the card connectors mounted on these electronic devices have an eject mechanism to eject the inserted card from the connector.
The conventional eject mechanisms are available in the following types:                One in which an insertion depth of the card is so set that the rear end of the inserted card protrudes from a card insertion opening and can be held by fingers of the user for withdrawing; and        One in which an eject button provided near the card insertion opening is pressed by the user after the use of the card to activate the eject mechanism to eject the card.        
In the former type, however, the card connector is required to have a dimension such that the rear end of the card protrudes from the connector for gripping by fingers. Not only does this impair the appearance of the connector but it also increases a chance of the card being damaged by external impacts and requires a large load to withdraw the card.
The latter type, on the other hand, has difficulty in locating the eject button at an appropriate position due to a limited space and also has a problem of the eject button impairing the appearance and hindering a size reduction.
To solve these problems Japanese Patent Application Laid-open No. 2000-251025 has been proposed. An exploded view of the proposed structure is shown in FIG. 12. With this conventional technology, a push-push type card ejection (which activates the card eject mechanism by pushing the inserted IC card again to eject it) is realized by using a heart-shaped cam and a cam lever.
In FIG. 12, the conventional eject mechanism has an eject member 100 with a triangular card abutment portion 101 against which a triangular cut-off corner portion of the card abuts, a coil spring 103 interposed between a housing lower plate 102 and the eject member 100, a guide groove 104 formed in the housing lower plate 102 to guide the movement of the eject member 100, a heart cam 105 formed in the housing lower plate 102, lever guide grooves 107a, 107b formed in the housing lower plate 102 around the heart cam 105 to guide the movement of a cam lever 108, and the cam lever 108 having one of its end secured to the eject member 100 and the other end moving through the lever guide grooves 107.
In this eject mechanism, when a card is inserted into the connector, the eject member 100 is pushed by the card through the card abutment portion 101 and is thus moved against the force of the coil spring 103 toward the rear of the connector. At this time, a front end portion 108a of the cam lever 108 moves along the lever guide groove 107a until it is locked at a recessed locking portion 105a of the heart cam 105. Now, the card is held immovable in the connector with the contact pads of the card in contact with the contact terminals of the connector.
When the card is to be ejected, the user slightly pushes the inserted card rearward. This disengages the cam lever 108 from the locking portion 105a of the heart cam 105, allowing the front end portion 108a of the cam lever 108 to be driven forwardly of the connector along the lever guide groove 107b by the recovering force of the coil spring 103. The eject member 100 therefore moves forwardly causing the card to be ejected by the card abutment portion 101 of the eject member 100.
If the eject mechanism is provided, for example, in a side wall of the connector housing, there would be a problem that the cam lever 108 may easily come off since the end of the cam lever 108 opposite the front end portion 108a is simply press-fitted into the eject member 100.
This kind of card connector often employs a metal cover as an upper housing to reduce the thickness of the card and increase the strength of the housing. The metal cover has a ground terminal formed at one end thereof through which the metal cover is connected to a ground electrode of a printed circuit board to release a static electricity accumulated in the metal cover.
The card connector with the ground terminal formed on the metal cover has a problem that when it is desired to realize card connectors with different height (thickness) specifications or different standoff specifications, a plurality of metal covers, which are relatively large and expensive parts in the card connector, need to be prepared corresponding to these specifications (i.e., a plurality of metal covers with ground terminals of different heights must be prepared). This increases the manufacturing cost.